Worm gears are often used when large swiftness reductions are needed. The reduction ratio is determined by the number of begins of the worm and amount of tooth on the worm gear. But worm gears have sliding contact which is noiseless but tends to produce heat and have relatively low transmission efficiency.
As for the materials for production, in general, worm is made from hard metal as the worm gear is manufactured out of relatively soft metallic such as aluminum bronze. This is because the number of teeth on the worm gear is relatively high compared to worm with its number of begins being usually 1 to 4, by reducing the worm equipment hardness, the friction on the worm the teeth is reduced. Another characteristic of worm manufacturing is the need of specific machine for gear cutting and tooth grinding of worms. The worm equipment, on the other hand, 
may be made out of the hobbing machine utilized for spur gears. But because of the different tooth shape, it is not possible to cut several gears at once by stacking the gear blanks as can be carried out with spur gears.
The applications for worm gears include equipment boxes, angling pole reels, guitar string tuning pegs, and in which a delicate quickness adjustment by utilizing a large speed reduction is necessary. When you can rotate the worm gear by worm, it is normally extremely hard to rotate worm utilizing the worm gear. This is called the personal locking feature. The self locking feature cannot always be assured and a separate method is preferred for accurate positive reverse prevention.
Also there exists duplex worm gear type. When using these, it is possible to change backlash, as when the teeth put on necessitates backlash adjustment, without needing a change in the guts distance. There are not too many manufacturers who can create this type of worm.
If you make the effort to develop your expertise of Worm wheel gear it could show quite lucrative in the long run.